Recently, technologies for information display using IC tags have been put to use. The IC tag is also called an RFID (radio frequency identification) tag, which is an ultra-small communication terminal in the shape of a tag (shipping tag) formed by embedding an IC chip storing predetermined information in a dielectric material, such as resin or glass, together with a radio antenna. From such an IC tag, product information stored in the IC chip is read off by radio communication. The memory of the IC chip, for example, is advantageous in that it can record several hundred bytes of data and can record producer information and many pieces of product information. An operator can read the recorded information from the IC tag in a non-contact manner. The IC tag is free from problems such as wear, and is advantageous in that it can be processed into a shape conformed to the form of a commercial product, and can be miniaturized or slimmed down.
For example, Patent Document 1 discloses that when an upper lid coupled to an external outer lid member covering a container lid to be mounted on a container mouth is opened, an antenna circuit provided in the outer lid member is cut, whereby the opening can be recognized. This Patent Document 1 teaches that producer information or product information can be read from the IC tag, or enables the opening of the lid to be recognized by detecting from an external reader the fact that the circuit of the IC tag is cut. Patent Document 1, however, still involves problems to be solved.